Field of the Invention
The present invention relates to a color filter substrate, a liquid crystal display device, and a method for manufacturing a color filter substrate.
This application is based on and claims priority from earlier Japanese Patent Application No. 2013-012006 filed Jan. 25, 2013, the description of which is incorporated herein by reference.
Discussion of the Background
Liquid crystal panels provided to generally used liquid crystal display devices have a configuration in which a liquid crystal layer is sandwiched between two substrates. For example, the two substrates each include a transparent substrate made such as of glass. Such a liquid crystal panel has a front side and a back side each of which is provided with a polarizing plate, or a polarizing plate and a retardation plate.
An organic electroluminescence display device (hereinafter referred to as organic EL display device) includes a white light-emitting organic EL in place of liquid crystal. The organic EL display device includes a color filter that includes a red filter, a green filter and a blue filter to enable color display. The organic EL display device is used as a high-definition display.
Patent Literature 1 (JP-A-2006-139058) and Patent Literature 2 (WO2007/148519) each disclose a color filter that includes a red filter, a green filter and a blue filter, in which the green filter is smaller than the red filter and the blue filter. However, neither of Patent Literatures 1 and 2 discloses a technique of configuring the green filter of a ½ pixel width with twice the number of lines of that of the red or blue filter (twice the number of picture elements when a ½ pixel is a picture element) so as to isolate the red filter from the blue filter. In Patent Literature 2, display of a green filter can be covered by the blue filter and a yellow filter, and thus, from a viewpoint of white balance, the red filter is required to have a relatively larger area. Neither of Patent Literatures 1 and 2 discloses color separation using stereoscopic image display, touch sensing, and an optical sensor.
Being able to perform three-dimensional display (stereoscopic display) or being able to control viewing angle, a liquid crystal display device displays an image using a backlight unit or an external light source. Being able to perform three-dimensional display or being able to control viewing angle, a liquid crystal display device controls the angle of light emitted from a surface of the liquid crystal panel toward an observer (to the outside) according to the purpose of display.
A liquid crystal display device or a display unit, which is able to perform three-dimensional display, uses various display methods. For example, three-dimensional displays include a method of using eye glasses and a method of not using eye glasses. The method of using eye glasses includes, for example, an anaglyph method that utilizes a color difference, or a polarized glasses method that utilizes polarization. In the method of using eye glasses, an observer is required to wear eye glasses dedicated to the three-dimensional display, which is annoying. Therefore, for three-dimensional display in recent years, there is an increasing need for a method that does not involve use of eye glasses.
In a technique under development, a light control element is set up on the front or back surface of a liquid crystal panel to adjust an angle of light emitted from the liquid crystal panel to a single observer (hereinafter may also referred to as a “binocular method”) or a plurality of observers (hereinafter may also referred to as “multilocular method”). The light control element may be used in a liquid crystal display device for a method of not using eye glasses.
As an example of the light control element, there is one that uses a lenticular lens in which optical lenses are two-dimensionally arrayed to realize regular refraction. Such a lenticular lens is formed by processing a transparent resin into a sheet shape, and may be used by being stuck onto the front or back surface of a liquid crystal display device.
Patent Literature 3 (JP-B-4010564) or Patent Literature 4 (JP-B-4213226) discloses a technique of three-dimensional display using a lenticular lens or a lenticular screen.
Patent Literature 5 (JP-A-2010-210982) discloses a parallax barrier for glasses-free three-dimensional display. Patent Literature 5 discloses in paragraphs [0016] and [0060] that a translucent film is provided between a parallax barrier and a color filter to keep a distance between the parallax barrier necessary for three-dimensional display and the color filter. However, the parallax barrier disclosed in Patent Literature 5 is chiefly electrically conductive, and there is no mention of increasing an aperture ratio using a relationship between a black matrix normally formed in the color filter and the parallax barrier. For example, Patent Literature 5 illustrates in FIG. 9 that the parallax barrier is arranged at a position overlapping with a portion of the color filter (blue filter, green filter and red filter), which may lower the transmittance. Patent Literature 5 shows in FIG. 10 what is estimated to be a cross-section structure of a pixel. Patent Literature 5 shows in FIG. 10 a black matrix. However, in FIG. 10 of Patent Literature 5, the parallax barrier is formed traversing the color filter. In this case, the transmittance is considered to be lowered. Further, when a parallax barrier is electrically conductive as in Patent Literature 5, it is difficult to apply touch sensing of electrostatic capacity type that is based on an in-cell method, because of the influence of the electrical conductivity of the parallax barrier.
A direct input method applied to a liquid crystal display screen includes an on-cell method in which a touch panel having a sensing function is set up on the front surface of a liquid crystal panel to have the touch panel receive input, and an in-cell method in which a sensing function, as a sensor with a matrix array, is formed in an array substrate or a color filter substrate of a liquid crystal display device so as to be internally provided in a liquid crystal cell.
Patent Literature 6 (JP-A-H10-171599) discloses a technique used for the on-cell method, that is, a touch panel based on a resistive film method, an electromagnetic induction method, an electrostatic capacity type method, and an optical method. In the on-cell method in which a touch panel is arranged on a surface of a liquid crystal panel, the thickness and weight of the touch panel are added to the thickness and weight of the liquid crystal display device, thereby increasing the thickness and weight of the device as a whole. Further, in the on-cell method, the quality of the liquid crystal display may be lowered due to the light reflection on the front surface of the touch panel and the internal surface of the touch panel.
In contrast, the in-cell method, in which a sensor is internally set up in the liquid crystal cell, is favorable because it is able to suppress the increase in the thickness of the liquid crystal display device and the lowering in the quality of liquid crystal display. An optical sensor as a sensor having a sensing function is under development.
Liquid crystal display devices used for information machine are increasingly used for three-dimensional display. For example, there are increasing technical needs such as of realizing a clicking feeling relative to a three-dimensionally displayed button, or preventing erroneous operation through finger input. For the detection of finger input, the on-cell method as mentioned above is used, for example, in which a touch panel is externally provided to a surface of a liquid crystal display. Alternatively, for the detection of finger input, the in-cell method as mentioned above may be used, in which an optical sensor is integrated into a liquid crystal panel. The liquid crystal display device integrating an optical sensor may require compensation of an optical sensor to prevent the occurrence of erroneous operation in relation to finger input, due to being influenced by temperature and a backlight light source.
A silicon photodiode may be used as an optical sensor, which includes a channel layer formed of polysilicon or amorphous silicon. In such a case, dark current may be caused due to the variation of environmental temperature or the like, and hence noise other than observation light may be applied to observation data.
Patent Literature 7 (JP-A-2002-335454) and Patent Literature 8 (JP-A-2007-018458) each disclose that dark current is subjected to operation/correction using a photodiode. These Patent Literatures 7 and 8 disclose a technique for dark current correction by using an imaging device.
Patent Literature 9 (JP-A-2009-151039) discloses that an S/N ratio of detection signals is improved by performing an operation based on the detection signals of a first light-receiving element and a second light-receiving element. However, Patent Literature 9 discloses no technique of performing color separation of visual light with good accuracy. In addition, according to claim 1 of Patent Literature 9, the first light-receiving element is provided thereon with an optical filter that absorbs light in the visible range, and a light-shielding member that absorbs and shields incident light. Thus, claim 1 of Patent Literature 9 seems to give no consideration to color separation of blue light, green light and red light. Furthermore, Patent Literature 9 does not disclose an alignment method used for manufacturing a color filter substrate. As described above, the technique disclosed in Patent Literature 9 relates to touch sensing for cancelling noise components.
Patent Literature 10 (JP-A-2010-186997) discloses a technique for an optical sensor (light-receiving element) that uses an oxide semiconductor. Patent Literature 10 chiefly discloses a technique for an optical sensor applied to a display that uses an organic material as a light-emitting layer.
Patent Literature 11 (JP-B-4857569) discloses that dry etching is applied to an image sensor, and to coloring of a first color. In Patent Literature 11, the pixel array is a Bayer array, but there is no mention of forming linear patterns with different line widths. A Bayer array may impair reproducibility in the corner portions of a green pixel. For example, in a liquid crystal display device or an organic EL display device, a Bayer array may vary the area ratios of colors, impair color balance, and cause color unevenness in display. A Bayer array, in which the area ratio of green pixels is twice of the area ratio of the blue pixels, is difficult to apply to a liquid crystal display device or an organic EL display device which places importance on white balance. In a liquid crystal display device or an organic EL display device having a Bayer array, it may be difficult to ensure reproducibility in displaying text (textual information) or consistency in stereoscopic display. Patent Literature 11 does not disclose contamination by using halogen and metal contained in organic pigments which are used in dry-etching a color filter layer. Patent Literature 11 does not disclose that, in coloring a second and the subsequent colors, fluidity at the time of heat curing is not utilized.
Patent Literature 12 (JP-A-2004-354662) discloses that a filter is overlapped with another filter. The overlapped portion of the two filters is projected compared to other portions and thus impair planarity of the color filter substrate. In general, a color filter has a thickness ranging from about 1.5 μm to 3 μm. Therefore, the overlapped portion of the two filters forms a projection of at least 1 μm which may cause alignment irregularity of the liquid crystal or deterioration in the quality of a liquid crystal image.    Patent Literature 1: JP-A-2006-139058    Patent Literature 2: WO2007/148519    Patent Literature 3: JP-B-4010564    Patent Literature 4: JP-B-4213226    Patent Literature 5: JP-A-2010-210982    Patent Literature 6: JP-A-H10-171599    Patent Literature 7: JP-A-2002-335454    Patent Literature 8: JP-A-2007-018458    Patent Literature 9: JP-A-2009-151039    Patent Literature 10: JP-A-2010-186997    Patent Literature 11: JP-B-4857569    Patent Literature 12: JP-A-2004-354662